A scaled down version of AVATAR undergoing aero-elastic test.
|Function||Manned reusable spaceplane|
|Country of origin||India|
|Launch sites||Satish Dhawan Space Centre|
|First flight||2025 (proposed)|
AVATAR (Sanskrit: अवतार) (from "Aerobic Vehicle for Transatmospheric Hypersonic Aerospace TrAnspoRtation") is a concept for a unmanned single-stage reusable spaceplane capable of horizontal takeoff and landing, by India's Defence Research and Development Organization along with Indian Space Research Organization and other research institutions. The mission concept is for low cost military and commercial satellite space launches, as well as for space tourism.
In January 2012, it was announced that a scaled prototype, called 'Reusable Launch Vehicle-Technology Demonstrator' (RLV-TD), was approved to be built and tested. The first scaled-down flight test is planned for July 2015, and the first orbital flight is proposed for 2025.
The idea is to develop a spaceplane vehicle that can takeoff from conventional airfields. Its liquid air cycle engine would collect air in the atmosphere on the way up, liquefy it, separate oxygen and store it on board for subsequent flight beyond the atmosphere. The AVATAR, a reusable launch vehicle (RLV) was first announced in May 1998 at the Aero India 98 exhibition held at Bangalore.
AVATAR is projected to weigh 25 tons, of which 60% of that mass would be liquid hydrogen fuel. The oxygen required by the vehicle for combustion in outer space would be collected from the atmosphere during takeoff, thus reducing the need to carry oxygen during launch. The notional specification is for a payload weighing up to 1,000 kg to low Earth orbit and to withstand up to 100 launches and reentries.
If built, AVATAR would takeoff horizontally like a conventional airplane from a conventional airstrip using turbo-ramjet engines that burn hydrogen and atmospheric oxygen. Once at a cruising altitude, the vehicle would use scramjet propulsion to accelerate from Mach 4 to Mach 8. During this cruising phase, an on-board system would collect air from the atmosphere, from which liquid oxygen would be separated and stored. The liquid oxygen collected would then be used to burn the stored hydrogen in the final flight phase to attain orbit. The vehicle would be designed to permit at least one hundred launches and atmospheric reentries.
AVATAR is being developed by India's Defence Research and Development Organization. Air Commodore Raghavan Gopalaswami, who is heading the project, made a presentation on the spaceplane at the global conference on propulsion at Salt Lake City, USA on July 10, 2001. Gopalaswami said the idea for AVATAR originated from the work published by the RAND Corporation of the United States in 1987.
In January 2012, ISRO announced that a scaled prototype, called Reusable Launch Vehicle-Technology Demonstrator (RLV-TD), was approved to be built and tested.
The aerodynamics characterization of the RLV-TD prototype was done by National Aerospace Laboratories in India. The unmanned scaled-down prototype has a diameter of 0.56 m and a length of 10 m. The RLV-TD is in the last stages of construction by a Hyderabad-based private company called CIM Technologies.
By May 2015, engineers at the Vikram Sarabhai Space Centre (VSSC) in Thumba Equatorial Rocket Launching Station were installing thermal tiles on the outer surface of the 'RLV-TD', so it can withstand the intense heat during atmospheric reentry. This prototype weighs around 1.5 tonnes and would fly up to an altitude of 70 km. ISRO has tentatively slated the prototype's test flight from the first launchpad of Satish Dhawan Space Centre for July 2015. The RLV-TD will be mounted on top of a rocket and launched beyond the atmosphere, after which the RLV-TD will separate and reenter the atmosphere while traveling through the hypersonic regime. The rocket is expendable while the RLV would glide back to Earth and fall in Bay of Bengal as there are no airstrips that are 5 km long in India that could be used to land such aircraft. ISRO has made detailed reports to construct an airstrip greater than 4 km long in the Sriharikota island and it will be built in near future. 
- Aircraft of comparable role, configuration and era
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